The present invention relates to a solid-liquid separator which can be widely used for food processing such as production of ground meat or bean-curd, processing of sludge water, processing in paper making, dredging of bottom sludge and the like.
A conventional solid-liquid separator is constituted so that an object to be processed containing a large amount of water is placed on onto a filter cloth, and the water portion flows down through the filter cloth, while the solid portion left on the filter cloth is recovered (refer to JPB 3568 (1988)).
However, such a type of solid-liquid separator has a disadvantage in that, since clogging of the filter cloth is caused, wash water under high pressure is injected onto the filter cloth after the solid portion has been removed therefrom, and the filter cloth is cleaned, thereby preventing it from clogging. This requires large amounts of wash water in the use of the conventional solid-liquid separator, resulting in a high running cost thereof.
Further, a large-sized filter cloth must be used for enhancing a capacity of processing sludge water, and a spray nozzle is required for injecting wash water under high pressure thereto, thereby making the device larger in size and bringing about a rise in the manufacturing cost.
Hereupon, the applicant proposed a solid-liquid separator in which a plurality of rings arranged in the axial direction with minute gaps left therebetween are connected with each other to form a cylinder, and a rotary shaft inserted through the inner space of the cylinder has a plurality of vanes arranged and secured spirally along the axial direction thereof to thereby constitute a screw conveyor, each vane being provided with a cleaning edge which is adapted to protrude into each of the gaps between said plurality of rings and return the solid portion which has entered into each of the gaps to the inner space of the cylinder (refer to Japanese patent application Hei-2253050).
This solid-liquid separator makes it possible to prevent the device from clogging without injecting wash water, thereby allowing a decrease in the running cost to be planned, and allows simplification of the construction of the device and a decrease in cost.
However, since this solid-liquid separator is so constituted that the cleaning edges projecting into the gaps between the plurality of rings are rotated to remove the solid portion which has entered in the gaps to clean the separator, there are problems in that the cleaning edges must be shaped thinner and at a higher precision, bringing about a rise in cost, and, at the same time, the edges are worn out in a relatively early stage or apt to be damaged so that the vanes with the cleaning edges shaped thereon must often be replaced by new ones. Moreover, since the screw conveyor is composed of a plurality of vanes secured to the rotary shaft and each cleaning edge shaped at the end of each of the vanes must be extended correctly into the gap between the rings, each of the vanes must be mounted on and fixed to the rotary shaft at a high precision, thereby bringing about a rise in cost.